Problem: $\dfrac{20}{100} + \dfrac{6}{10} = {?}$
The fractions must have the same denominator before you can add them. Rewrite $\dfrac{6}{10}$ as $\dfrac{60}{100}$ $\dfrac{20}{100} + \dfrac{60}{100} = {?}$ $ = \dfrac{80}{100}$